A cable tie locking structure for locking a distal end of the cable tie to a proximal end so as to keep the tie wrapped around and holding together material to be bundled, such as the one described in Patent Document 1, for example, is known. In the cable tie locking structure of this type, the cable tie includes a strap portion and a head portion. The strap portion is formed as a strap and includes a first locking hole that extends through in a thickness direction at the proximal end.
The head portion can let the strap portion pass therethrough, and is provided so as to surround the proximal end and the distal end of the strap portion that are overlapped upon one another, and is secured to the proximal end. The head portion includes a second locking hole and a through hole at positions respectively facing the proximal end and the distal end of the strap portion to coincide with the first locking hole of the strap portion.
At the distal end of the strap portion, at a point where the first locking hole and the second locking hole coincide with each other, there is provided, with the use of a punch member of a cable tie tool, a protruded portion that protrudes through the first locking hole and into the second locking hole. The protruded portion makes engagement with a first inner wall surface of the first locking hole and a second inner wall surface of the second locking hole so that the distal end of the strap portion is secured to the head portion and to the proximal end of the strap portion.
However, in this cable tie locking structure, the protruded portion is formed by means of the punch member in a hollow conical or columnar shape. The protruded portion thus engages with the first inner wall surface of the first locking hole and the second inner wall surface of the second locking hole in a relatively small area. Therefore, when the cable tie being used has a relatively large width in the short-side direction of the strap portion in comparison to this area, there is a possibility that the protruded portion goes out of engagement and the distal end of the strap portion is released from the head portion, if the distal end of the strap portion is pulled by the material to be bundled which is wrapped and held together by the tie, in a direction in which it is pulled out of the head portion. Namely, in some cases the distal end of the cable tie may not be secured to the proximal end firmly enough.